PAL-Timing scheme for a bad scan line, at least the sprites 3-7 active on the
current scan line and the sprites 0-2 on the following scan line:
+---------------------------------------------------------------+
| 1 2 3 4 5 6 |
|123456789012345678901234567890123456789012345678901234567890123|Cycles
+---------[------(--------------------------------------)---]---+Borders
|3s4s5s6s7srrrrrgggggggggggggggggggggggggggggggggggggggg-N0s1s2s|Phi-1 VIC
|ssssssssss cccccccccccccccccccccccccccccccccccccccc ssssss|Phi-2 VIC
|==========xXXX========================================***======|Phi-2 CPU
+---------------------------------------------------------------+
'-' = idle bus cycle (reads from the last byte of the video bank)
<num> = pointer fetch for sprite <num> ; g = graphics fetch
r = memory refresh cycle ; c = character pointer and/or color data fetch
s = sprite data fetch ; N = extra '-' cycles for NTSC added here
x = processor executes instructions (BA high, AEC high)
X = bus request pending, bus still available (BA low, AEC high);
processor may execute write cycles, stops on the next read cycle.
'*' = bus request pending, bus still available (BA low, AEC high);
processor is blocked because it would like to read something.
'=' = bus unavailable (BA low, AEC low); processor is blocked because it
would like to read something.